This application discloses a communications network and a related device. In one embodiment, the communications network includes a first optical line terminal and a second optical line terminal. The first optical line terminal is configured to send, through a first passive optical network (PON) interface based on a first PON protocol, a first optical signal to the at least one second optical line terminal. The second optical line terminal is configured to process the first optical signal and send through a second PON interface based on a second PON protocol, a processed first optical signal to at least one customer-premises equipment during downstream data transmissions, and process a second optical signal and send, through the first PON interface based on the first PON protocol, the processed second optical signal to the first optical line terminal during upstream data transmissions.